1. Field of the Invention
This invention relates to one-pot thermosetting coating compositions. 2. Description of the Prior Art
Two-pot polyurethane coating compositions which comprise a polyfunctional isocyanate and an active hydrogen compound are well known. Also known are polyurethane coating compositions which are prepared from "one-pot" formulations, for example, that described by Levy in U.S. Pat. No. 3,694,389 wherein a ketoxime-blocked polyisocyanate is used instead of the usual unblocked polyisocyanate. The use of oxazolidine as a substitute for amine or alcohol active hydrogen compounds is also known, for example see Emmons U.S. Pat. No. 3,743,626. The advantage of one-pot systems is extended pot life, but a disadvantage of prior one-pot systems is that they require high curing temperatures which, in many applications, damages the substrate which is to be coated. The advantage of two component systems versus the above-described one component systems is low temperature cure. However, the industry still desires a one-pot polyurethane coating system with extended pot life as well as low temperature cure. To date such compositions have not been available, in spite of the industrial demand for them.
It is an object of the present invention to provide such one component, low temperature cure thermosetting polyurethane coating compositions. A further object is to provide a process for using such compositions. A still further object is to provide a cured coating composition prepared at low temperature from a one pot system, particularly for substrates sensitive to high temperatures, such as plastics, wood, paper and leather, although other substrates such as metal may also be used.